C :

#include<stdio.h>
#include<string.h>
#define MAXN 16

int a[MAXN][MAXN];

int main()
{
	int n, x, y, tot = 0;
	scanf("%d", &n);
	memset(a, 0, sizeof(a));
	tot = a[x = 0][y = n-1] = 1;
	while(tot < n*n)
	{
		while(x+1< n && !a[x+1][y])
		{
			a[++x][y] = ++tot;
		}
		while(y-1>=0 && !a[x][y-1])
		{
			a[x][--y] = ++tot;
		}
		while(x-1>=0 && !a[x-1][y])
		{
			a[--x][y] = ++tot;
		}
		while(y+1<n && !a[x][y+1])
		{
			a[x][++y] = ++tot; 
		}
	}
	for(x = 0; x < n; x++)
	{
		for(y = 0; y < n; y++)
		{
			printf("%5d", a[x][y]);
		}
		printf("\n");
	}
	return 0;
}